1. Field of the Invention
The present invention relates to the structural reinforcements for a vehicle roof and windshield.
2. Background Art
Vehicles are assembled with structural members inside of outer body panels that are used to support the roof and windshield of the vehicle. Generally a roof rail is provided to support the vehicle roof that must meet roof crush resistance standards. Vehicle windshields are, in part, supported by what is commonly referred to as an A-pillar. Other pillars supporting the roof are referred to as a B-pillar, a C-pillar and in some car designs a D-pillar. Recently, heightened standards for roof crush resistance have been set that create challenges for vehicle designs and manufacturing processes.
Conventional A-pillars and roof rails are formed by the assembly of multiple stamped parts together by resistance welding, or spot welding, production processes. Some measure of increase roof strength may be obtained with conventional manufacturing techniques by substituting high strength steels but this approach increases the cost of the vehicle.
Hydroformed roof rails and hydroformed A-pillars have been proposed that feature tubular members that provide manufacturing challenges due to the closed cross section of the tubular member. Hydroformed structural members offer advantages relating to the inherent load carrying capacity of tubular structural members. Load carrying capacity of structural members is critical for optimizing roof strength performance.
Sizeable access holes may be required to be provided in the wall of the tubular supports through which a resistence welding gun may be used to weld the tube to other parts. However, forming access holes in the wall of the tubular member defeats the purpose of using a hydroformed tubular member since it weakens the tubular member.
As an alternative, single siding welding techniques such as MIG welding or TIG welding may be used to weld brackets and other parts to a tubular frame member. The use of single siding welding techniques requires additional capital investment and expense relating to making the single sided weld and verifying the integrity of such welds.
Stamped brackets that are attached to a hydroformed tubular A-pillar or roof rail must be assembled to close tolerances in the area of the windshield header and windshield. Stamped brackets for securing the hydroformed tubular members to the vehicle add weight to the vehicle.
The above problems relating to conventional roof rail and A-pillar assemblies and hydroformed tubular supports are addressed by applicants' invention. These and other challenges that may be solved by applicants' invention are summarized below.